ruler4

Rendered HTML

ruler5

Unlike `***` and `___`, for `---` to be recognized as ruler,
---
it must be preceded by a blank line.
`- - -`, on the other hand, is always recognized as ruler:
- - -

Rendered HTML

<p>Unlike <code>&#42;&#42;&#42;</code> and <code>&#95;&#95;&#95;</code>, for <code>---</code> to be recognized as ruler,
</p><hr>
<p>it must be preceded by a blank line.
<code>- - -</code>, on the other hand, is always recognized as ruler:
</p><hr>

ruler-in-codeblock0

Lines with any of the following character sequences as sole content
* * *
- - -
_ _ _
***
---
___
get rendered as HTML `hr` elements.
Note that "---" rulers are only recognized after blank lines
to de-ambiguate from setext-style headers.

Rendered HTML

<p>Lines with any of the following character sequences as sole content
</p><pre><code> * * *
- - -
_ _ _
***
---
___
</code></pre><p>get rendered as HTML <code>hr</code> elements.
</p><p>Note that "---" rulers are only recognized after blank lines
to de-ambiguate from setext-style headers.
</p>